Piston structure



ct. 14, 1952 J, BUTTERFIELD 2,614,009

PISTON STRUCTURE Filed March 24, 19 48 4 Sheets-Sheet 1 FTfR/I EY 1952 J. P. BUTTERFIELD 2,614,909

PISTON STRUCTURE Filed March 24, 1948 4 Sheets-Sheet 2 I a /2 k 17772523 5145.

1952 J. P. BUTTERFIELD 2,61

PISTON STRUCTURE Filed March 24, 1948 4 Sheets-Sheet 3 Oct. 14, 1952 J. P. BUTTERFIELD PISTON STRUCTURE Filed March 24, 1948 4 Sheets-Sheet 4 Patented Oct. 14, 1952 PISTON STRUCTURE John P. Butterfield, Grosse Pointe Woods, Mich assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application March 24, 1948;, Serial No. 16,6l9

13 Claims. 1

This invention relates to piston structures of the type used in internal combustion eng e and particularly engines or compressors, of the double acting type in which a working head, is provided at eachwend of the piston structure.

In engines of the double acting typeit is customary to operably connect the piston structure directly tov the crank portion of the crankshaft without the use of a connecting rod such as is used in the more conventional single acting types of engines. However, in such arrangements, difliculties have been experienced in providing an arrangement in which undue wear and clearances will not develop between the piston structure and crankshaft and in which the operating parts, including the piston structure. crankshaft, and their connecting parts, will not be subjected to undesired binding due to un-' avoidableerrors in the manufacture and assembly of the engine within the range of tolerances customarily provided.

It is an object of my invention to provide improvements which will avoid or largely overcome the aforesaid past difiiculties, the subject invention being directed to an improved piston structure for accomplishing the desired results.

A further object is to provide an improved piston structure provided with a slideway for receiving a crank-mounted bearing block, the slideway having opposed slideway bearing surfaces formed cylindrically about the axis of the slideway as an axis of generation of the slideway.

bearing surfaces. By reason of such arrangement the bearing block is axially located on the crank portion and the parts capable of a universal self -adjustment to relieve any binding tendencies, the piston structure being free to oscillate slightly to sufiiciently relieve such binding tendencies.

My invention, according to certain features thereof including the provision of my improved slideway as a part of the piston structure, may be utilized in a unitary or one-piece type of piston structure or may be utilized in a piston structure of the type formed of several parts and it is accordingly a further object of my invention to provide a piston structure of each of these types capable of providing the aforesaid desired improvements.

In piston structures that are in effect two pistons directly coupled to one another and receiving a crankshaft between them, it is'a problem to construct the piston structure in such a way that it and the crankshaft may be readily-assembled. This is particularly true if the piston structure is relatively short, which 2 g I have .found to be desirable in .cases-where-ia savingin space occupied. by the. engine ne a the piston structureis to be effected. An additional object-of theinvention 15; to provide an improved pistonstructureemploying a plurality of piston parts joined to one another. A further object is to provideimprovementsin a: piston structure involving. opposed pressure faces and receiving a, crankshaft -eiiteI1diI-13 throughthepistonstructure. Additional objects and advantagessoftmy in. vention will be more apparent from the follow: ing description of 7 several embodiments oi-my invention which are illustrativeof theprinciples thereof, referencebeingmade to the accompanying. drawings in. whichz Fig 1 is aside. .elevational view taken' iro nline ll 'oflFign5 of a.- novel piston. partiorming part of the present invention;

Fig. 2 is anenlarged sectional iview..taken-;on thelineL-Zof Fig. 1; v Fig. 3 is .a sideview of twopiston. partsreafiy to be assembled .with respectito one another; Fig. 4 is asectionalviewtaken..on.-the.--line 4-4 of'Fig.3;. I 4, Fig, 5 is asectional view taken on thelinesii oi.Fig. 3;, Fig. disasectional .view taken, on :the line $6.oi Fig. 5; F Fig. -7 is. a. sectional view through an 7. engine employing. the novel piston structure .ofthe pres.-

ent=invention-';

Fig. 8 is an elevational .view of a. piston strnc-g ture according to a iurtherembodiment of my im vention Fig.- ..9- is a sectional. viewtaken on. line ,-9-,--9 f -Fig 8;; I. ,1 i Fig; 1.0 is a sectional -.viewtaken-on line. Hielli of Fi .9,

. Thereference character lildesignates amnitary piston part of a-piston structure, such part-ham; ing a pressure head ll, a'-skirt--l2-,-intersecting diametrical webs orflanges-I3 and I l, extending inwardly from the head and from: onetsidaof the skirt to theoppositaside, and a slideway portion l 5 extendingalongc'the flange-l 4 in spaced relation to'thehead- H from-one-.side-ofethe skirt ,l 2 to the other side, the slideway bEiIlEyOPGH outwardly-of the skirt. Each of the X-braces formed bythe websl3=and l l 'ateachnendqof the piston structure has these websfsorarranged that they interconnect a head I l and? skirt --,I:-2, and sweep into merging relationship with the slideway as best seen in Figs. 6*an'dr71., -As-seen 56 infFigs..;2', 5, and :Wtheslideway: portion [i is wider than the flange 4 and is provided with an arcuate cylindrical bearing surface of revolution l6, formed of elements or lines, all of which are parallel to one another and to the slideway axis l6a about which the surface I6 is developed as a portion of a cylindrical surface having its axis at l6a.

The skirt II has four projections H, which, as seen in Fig. 6 are disposed adjacent to and at opposite sides of the ends of the slideway portion l5, and which, as seen in Figs. 2, 3, and 6, extend farther inwardly from the piston head than the slideway portion I is spaced therefrom. Each skirt projection I! has a cylindrical outer face Ila and is provided with a passage I3 extending from the projection end and toward the piston head and terminating at a region spaced therefrom at which is provided a recess or opening IS in the piston skirt. These projections I! provide the intermediate body portion or intermediate connecting structure of the whole piston structure when the main component parts |ll thereof are assembled. Regions 2!) of the skirt at opposite sides of the slideway portion l5 between the projections extend inwardly from the piston head I! a less distance than the slideway portion i5 is spaced from the piston head. As seen in Fig. 7, the depth of the flange l3 varies so as to have a minimum adjacent skirt |2 somewhat less than the length of the skirt region 20 and. a maximum adjacent the slideway portion l5 so that the flange 3 merges with the slideway portion. The flange l4 also merges with the slideway and extends transversely to flange l3 between the head and skirt l2. Flanges l3 and I4 provide an X-brace stiff support for the slideway rigidly connecting the head, skirt, and slideway while providing a light weight piston structure.

The illustrated piston head H has a pressure surface that has portions angularly related to one another althou h, if desired, other shapes ofpressure surfaces may be used as desired.

The piston part Hi, just described, is adapted, as shown in Fi 7, to be secured to a similar piston part ID with the skirt projections I! of one piston part abutting those of the other piston part and the slidewav portions l5 embracing a bearing block or a slide head 2|, in which is mounted a bushing 22, in which an offset crank portion 23 of a crankshaft structure 24 is journalled. For convenience of as embly the slidehead is formed in halves meeting along a plane 25. The bearing block halves are'secured to-- gether at their opposite sides by suitable means 25' shown in Fig. 7. Each slidehead half has an arcuate cylindrical surface portion 25a which matches and slides along the arcuate cylindrical surface IS in one piston part ID. The bushing 22 is also formed in halves so that like the slidehead 2| it may be easily assembled on the crankshaft portion 23.

The plane 25 contains the slideway axis I80. and also the axis of the crank portion 23 such that the slideway axis Ilia is normal or perpendicular to the axis of the crank portion 23. Furthermore the plane 25 is normal to the axis 25b of the en ine cylinder and piston structure as shown in Fig. 7. The three axes 25b, Mia, and the axis of crank portion 23 intersect at a common point within the slideway and within the bearing block 2| when the piston structure is at its two extreme positions of movement, one being shown in Fig. 7.

It will be understood that when the piston parts are assembled, the two cylindrical bearing surfaces l6 have a common axis |6a which is also the axis about which the cylindrical bearing block surfaces 25a are formed. The bearing block 2| is axially slidable on the crank portion 23 and is, therefore, free to adjust itself in relation to the crank and piston. Inasmuch as the. bearing block 2| is freely slidable in the direction of axis |6a and since the piston structure can oscillate or tilt slightly about the crank pin 23 within the cylinder bore 39 it will be apparent that any minor misalignments or deflections of the crankshaft, crank portion, piston, cylinder bore, or bearing block, are fully compensated for by the ability of these parts to freely adjust themselves in universal fashion as more fully described and claimed in my copending application Serial No. 16,648 filed March 24, 1948.

It will be apparent that each of the bearing surfaces l6 of the slideway is cylindrically curved in planes normal or perpendicular to the slideway axis Ifia.

The piston parts In are held in assembled relation by four tension members or bolts 26 and eight nuts 21. Each bolt is positioned in a passage IS in one piston part I0 and in the passage I8 aligned with the aforesaid passage in the other piston part I0 and has threaded ends 28 projecting into the openings IS in the piston skirts The nuts 27 are inserted in the openings l9 and applied to the threaded ends 28 until they are drawn up tight against washers 28 acting against the bases of the openings IS. The pressure heads I l are thus tied together by tension tie members in the form of bolts 26 embedded in the structure |7 intermediate the opposite ends of the assembled piston structure. The provision of the two main component similar piston parts I 0 facilitates assembly of the doubleheaded piston structure resulting from mounting the two piston parts on the same portion of crankshaft 24.

The crankshaft has axial portions 30, 3|, and 32 journalled respectively, in bearing 33, 34, and 35 supported in blocks 35 and 37, having cylinders 39', in which the pistons reciprocate. Heads 38 and 39 are secured to the cylinder blocks 36 and 37, respectively. The blocks 36 and 37 are bolted together in face contact in a plane through the crankshaft axis normal to axis 25b.

The mating cylindrical surfaces on the slidehead 2| and on the slideway portions l5 insure that the slidehead is self-locating with respect to the slideway, i. e., shifted the correct amount to left or right as viewed in Fig. 7 for the siidehead to occupy a mid position with respect to the slidehead and the crankshaft portion 23; and that the slidehead is self-aligning with respect to the slideway, i. e., is angled properly in relation to the line of reciprocation along which the slidehead travels, which is transverse to the plane of Fig. 7.

The machine comprising the cylinder blocks 36 and 37, the heads 38 and 39, the crankshaft 24, and the multi-part piston structures directly mounted on the crankshaft 24 may be either a pump or an engine, depending on whether the crankshaft reciprocates the piston structures and they in turn pump fluid in and out of the cylinders or whether an explosive mixture admitted to the cylinders drives the piston structures and they in turn rotate the crankshaft.

It will be noted that all portions of my piston structure, including the means I! and 26 for tieing the piston head portions |l together, lie entirely within the cylinder bore 39 which is of a uniform horeoand entirelywithinannxialprojem .:the"pistonheadportions. Thezinnerrsnre iaceidl oizeachv projection '11.; is-gitormedicenvex in the direction:of'a planeinormal to the axis of the prstonstructureat least :lni'the region. midway between the siideway SUTfaEBSSI-S in iorderto provide sufiicie'nt metal to embed tthetholts ;25:and also togive the :intermediate structureioi; the piston suificient-tstrength. lnzorderrto :avoi'dflinten .Ierence mechanically with .the. crankshaft. the oblique portions'i2'3 of "crankshaft: 24 are. concaved at 42 50 that theywill :sweepwith minimum clearance the surfaces l l of the skirtfprojections 1''! adjacent thereto during the midi-stroke of. the piston-structure.- This arrangement is: of :advantage, in providing engine compactness andmay be. employed in eonnectionwithone piece pistons as, for example, the Fig; 8. piston which iscast integrally without the bolts -26 andis preferably employed with a built-up crankshaft toZfacilitate assembly'as"hereinafter referred to.

In order to accommodate movement 'of the piston structure throughout its stroke-without interferencewith the crankshaft'and to provide for threading of the crankshaft through the piston structure; the latter is provided at each side of the *slideway ldwith aslot or opening- 19' elongated in the direction of the piston axis'to receive the crankshaft journal portions; 3-1, and 32 ad- 'jacent "the obliquelyprank portions -23. The

diametrically disposed openings 40 are provided bythe adjacent projections at each -side of slideway -l'5 and byth'e :skirt, it 'be'in zapparent that the slot 40 mus't extend to each side of plane 25 outwardly in the direction of the piston axis beyond the sl'ideway portions of the piston parts 1-0; Eachpis'ton's'kirfi l z is proy'ided with a set-of piston rings l-l-a.

Referring now t'o Figs. 8 tofll',I"have illustrated a modified type of piston s'tructurewhich' may .be sulostitutedlfor that previously :r-ef erred to herein. pistonvstructure is termed as an integral or unitary casting and for convenience of assembly on a crankshaft structure :the 3lB.-trt81' may be of thebuilt-up type ot-which many'formsare known in the one being illustrated-rinmy impending application- Serial No; 1636146; filediMarch 24'; .1948. unitary piston structure pressure headsi l l" kconnec'ted wby' an intermediate Ebody-ti'e portion or connecting-structure Fl"-=corresponding respectively *with the: aforesaid heads I l and connecting structure-1:1 oi the'built up; two-part, piston structure shown in :Figures -1-' 7.' .I-Ioweven in-Fig: SE'the tie structure 1"! comprises a 'Lmitary portion of the -piston structure :betweenskirt :por-

tionsil2. "Webs or'fianges i3" and M correspond generally to "the aforesaid -webs l 3 and -i-4-and provide the -.X-brace support for theheads; skirt, andislidewayportions l5 which-are constructed ius-t -as aforesaid in connection with the two-part piston structure. Likewise therelon'gatedslots-40' accommodate the crankshaitfjust as" recited. in cormection-with slots .48, these slots :40! being bounded -ontheir=sides by the-pairs oftiesll which are=disposed adjacent the-ends of the slide-- way 15 and-Which lie on the same-side thereof.

7 .In use; the-piston structure of Figs. 8 to. 10 functions aj-ust as .hereinbefore set forth tor the Fig. Hassembly, it .beingunderstood that the slideway will receive the. aforesaid bearing block -2 I in the. :same relationship .withthe. crank portion of a crankshaft structure. The...'E'ig...8 piston structure Ilikewisehas all of its-parts contained with-in -a-lzzylinderbore of uniform. dimension -th-roughout, ..in .theQinterests. ofmaximum 6 simplicity.tenginercompactnessrand economy of construction. and: opera-tingacostsn Features-of Imvelty'; not .claimed; but:disclosed in' this. :applicationare more .fnlly; disolosedand claimed. intthe .cQpending: applicationssof. .Alex ander G; Herreshofi' Serial No. 16,801,f1led.Marcli 24, 19.48;. and John.1?.;.Butterfield.-:Serial Nos. 163645, 516,547; now': Patent .No; 2,571,193 .zissue'd 0ctoberrl6; r1951, '16 5&8; and 16,650,; filed-I 24, I948.

I claim:

1-...A .pistonrstructure :having: pressure :faces. at opposite ends and a tubular 'skirt portion connectedtherebetween having .a transverse 'slideway formed within theintermediate'regionof the skirt portion, :the piston structure being formed of a pair-coi :matingparts each having'one outersend iorminga pressure face or the piston-structure and the-opposite innerend designed for-engaging the corresponding opposite inner end of theother mating part, the siideway comprising: opposed; concavely curved, bearing portions, one. formed in each mating part, each mating part having a plurality of generally parallel passages extending from'thensaid'inner end'thereof to a portion or the skirt spaced from the said outer'end'thereof and recesses formed' in thes'kirt at the said portions' of the skirt intersecting said passages, the passages in one mating part being generally aligned with the passages in the other-mating part, a plurality of bolts "each of which is positioned in an aligned set of the passagesin'tthe mating parts and each having threaded. ends located in' the'recesses, and inuts'engagingthe threaded ends of "the bolts 'and portions "or the matingparts at'the recesses for holding themat ing' parts "together.

'2'. A 'pistonstructure comprising a. pair of mateingparts'a'daptedto embrace a crank shaft, each mating part comprising a head, a skirt extending from'the head, a pair of flanges within each .part extendingirom the head in intersecting relation with one'another. from one side of the skirt to the other, a slideway portion within the piston fhaving a curved .bearing surface extendingfrom one side of the .skirt to .the other alongone flange in spacedire'lation .to the head, theskirt having longitudinally extending projections at opposite sides of the ends of the slideway portion extend:- ing farther from the head than the sli'dewjay portion' is; spaced therefrom,}the skirt projections having longitudinally ex'tending. passages there? through. they shut. projections ofjone mating pert abuttingthe skirt projections .of the other mating ,pa'rt withv the passages 'thereoi generallyaligned and thecurved .slideway hearing parts in facing, spaced, relation, and .means positioned in f the passages for holdingthe mating .parts together.

'3. A pistonstructure compr'isingapairofmate ingfparts adapted to.embrace-..a crankshaft, each matingpart comprising a head, askirt extending from the head, a pair. of stiffeningilanges .within each part extending from the headin intersecting relation with one anotherfrom one siderof the skirt-to. the. other, a .slideway. portion having. .a curved bearing surface extending Q from one or the skirt to the other along .one .fiange. in spaced relation to the head, the skirthavinglongi'tudinally extending projections. at. opposite sides of the endsoi. the slideway portion extending farther iromjthelhead thanQtheslidewaYhortion is spaced therefrom, .there. .being longitudinally. extending passages through the projections terminating in regions o'fflthev skirt spaced from the head, recesses f -ormeclat the saidregions of the skirt intersecting said passages, the skirt projections of one mating part abutting the skirt projections of the other mating part with the passages thereof generally aligned, and the slideway bearing portions in facing, spaced, relation, bolts positioned in the passages having threaded ends in the recesses, and nuts engaging the threaded ends and the mating parts to hold the latter together, the portions of the skirt projections adjacent said passages being enlarged to further stiffen the piston structure.

4. The piston structure specified in claim 3, regions of the skirt of each mating part at opposite sides of the middle of the slideway portion terminating a less distance from the head than the slideway portion, the flange intersecting the flange associated with the slideway portion increasing in depth from the said skirt regions to the slideway portion to correspond to the depth of said skirt regions and to the spacing of the slideway portion from the head.

5. A piston structure comprising a pressure head at each end thereof, a slideway within said structure having its axis extending transversely of the axis of the piston structure, said slideway comprising a pair of spaced, curved bearing surfaces each comprising a bearing surface having said slideway axis as its axis of curvature, and tie means connecting said heads and comprising a tension element embedded in said piston structure, and X-brace flanges within said structure extending between each pressure head and the slideway.

' 6. A piston structure comprising a pressure head at each end thereof, a slideway within said structure having its axis extending transversely of the axis of the piston structure, said slideway comprising a pair of opposed, curved bearing surfaces each comprising a bearing surface having said slideway axis as its axis of curvature, said piston structure including skirt portions having a pair of diametrically disposed crankshaft-receiving slots therein extending axially of the piston structure from an intermediate region thereof beyond said slideway whereby opposite ends of said slots are respectively disposed closer to said heads than said slideway bearing surfaces, and X-brace flanges within said structure extending between the heads and skirt portions and the slideway.

'7. A piston structure of the character described comprising, in combination, a pressure head at each end of said piston structure, a slideway extending transversely of the axis of said piston structure, and an X-brace between each of said heads and said slideway, each of said X-braces comprising a pair of webs each being swept into merging relationship with said slideway, said slideway comprising a pair of bearing surfaces relatively spaced apart axially of the piston structure, said surfaces being formed as portions of a common cylinder.

8. A piston structure of the character described comprising, in combination, a pressure head at each end of said structure, said piston structure having an internal slideway extending therethrough on an axis normal to the axis of said piston structure, said slideway having curved bearing surfaces formed as portions of a cylinder having an axis coinciding with the slideway axis, and a pair of crankshaft-receiving, diametrically opposed, openings each disposed between the ends of said slideway in a direction circumferentially of said piston structure, said piston structure comprising a plurality of intermediate structural portions disposed between said heads in a direction axially of the piston structure, said intermediate portions being resp ctive y disposed between said openings and the ends of said slideway in a direction circumferentially of said piston structure, said intermediate portions having outer cylinder-engageable cylindrical surfaces and inner surfaces convex in a plane normal to the axis of the piston structure containing the axis of said slideway, and means for securing said heads together including a plurality of tension members extending axially of said piston structure and respectively embedded in said intermediate portions.

9. A double ended piston structure having at each end a pressure head, a skirt portion extending between the pressure heads, a slideway portion Within the skirt portion extending transverse :to the axis of the piston structure, a pair of stiffening flanges within the piston structure extending from each head in intersecting relationship with one another and extending from one side of the skirt to the other, one flange of each pair extending along the slideway, curved bearing surfaces along the slideway formed as portions of a cylinder having its axis coincident with the axis of the slideway, and diametrically disposed crankshaft receiving slots formed in the skirt portion arranged at a distance spaced circumferentially from the ends of the slideway.

10. A double-ended piston structure having at each end a pressure head, a tubular skirt portion connecting the spaced pressure heads, axially extending, diametrically disposed, slots piercing the walls of said tubular skirt portion, a flange depending from the inner side of each pressure head arranged to extend diametrically across said skirt portion, a bearing block slideway supported by and aligned with each of the depending flanges throughout their length, said slide- :ways being aligned with and spaced from each other with the opposed faces of the spaced slideways formed as sections of a single cylindrical surface, and additional flange means depending from each pressure head and arranged in intersecting relationship with respect to said first mentioned slideway supporting flanges intermediate the ends of the slideways, said additional flanges being connected to said slideways and adapted to stiffen the support for said slideways intermediate the ends thereof.

11. A piston structure comprising a pair of mating parts adapted to embrace a crankshaft. each mating part comprising a pressure head, and a tubular skirt portion depending from the pressure head, a pair of flanges within each skirt portion depending from the inner surface of the pressure head and arranged to extend axially of the skirt portion in intersecting relation with respect to one another, a slideway portion supported by said flanges arranged to extend from one side of the skirt to the other along one of the flanges in axially spaced relation to the pressure head, said slideway having a curved, axially extending, bearing face, the skirt having axially extending projections at opposite sides of the ends of the slideway portion extending farther in an axial direction from the pressure head than the slideway portion is spaced therefrom, passages in said projections extending lengthwise thereof, the skirt projections of one mating part abutting the skirt projections of the other mating part with the passages therein generally aligned and the slideways arranged in opposed, aligned, spaced relation, and means positioned in the passages for holding the mating parts together.

12. A piston structure comprising a pair of mating parts adapted to embrace a crankshaft, each mating part comprising a pressure head, and a tubular skirt portion depending from the pressure head, a pair of flanges within each skirt portion depending from the inner surface of the pressure head and arranged to extend axially of the skirt portion in intersecting relation with respect to one another, a slideway portion supported by said flanges arranged to extend from one side of the skirt to the other along one of the flanges in axially spaced relation to the pressure head, said slideway having a curved, axially extending, bearing face, the skirt having axially extending projections at opposite sides of the ends of the slideway portion extending farther in an axial direction from the pressure head than the slideway portion is spaced therefrom, passages in said projections extending lengthwise thereof, the skirt projections of one mating part abutting the skirt projections of the other mating part with the passages therein generally aligned and the slideways arranged in opposed, aligned, spaced relation, the opposed bearing faces of said slideway portions being formed as portions of the same cylindrical surface, and means positioned in the passages for holding the mating parts together.

13. A piston structure comprising a pair of mating parts adapted to embrace a crankshaft, each mating part comprising a pressure head, and a tubular skirt portion depending from the pressure head, a flange depending from the inner surface of the pressure head and arranged to extend axially of the skirt portion, a bearing block 10 slideway portion supported by the flange arranged to extend diametrically of the skirt portion in axially spaced relationship to the pressure head, said slideway having a curved, axially extending, bearing face, the skirt having axially extending projections at opposite sides of the ends of the slideway portion extending farther in an axial direction from the pressure head than the slideway portion is spaced therefrom, passages in said projections extending lengthwise thereof, the skirt projections of one mating part abutting the skirt projections of the other mating part with the passages therein generally aligned and the slideways arranged in opposed, aligned, spaced relation, and means positioned in the passages for holding the mating parts together.

JOHN P. BUTIERFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 695,824 Motsinger Mar. 18, 1902 870,559 Hogan Nov. 12, 1907 1,042,505 Twombly Oct. 29, 1912 1,710,721 Bosmans Apr. 30, 1929 2,143,586 Walti Jan. 10, 1939 2,200,199 Bradfute, Jr. May '7, 1940 2,404,906 Heald' July 30, 1946 FOREIGN PATENTS Number Country Date 1 491,513 France nqzwonnv Feb; 19 

